It was odd for a man to be pacing around his front yard in the wee hours of a chilly October morning. As Seattle police and paramedics pulled closer, however, they noticed something even stranger: The pacing man, 29-year-old Donyea Jones, was burned so badly, the flesh was literally melting off his frame. "My wife poured gasoline on me and lit me on fire," he explained calmly before being rushed to nearby Harborview Medical Center, where he died of his injuries several hours later.

Tonya Michelle Jones, who'd called 911 at least four times, was arrested at the scene. The pair had apparently been fighting for days over Donyea's alleged infidelity, and they were no longer sleeping in the same bedroom. The night before, when he was high on marijuana, Donyea had threatened Tonya with a gun. Tonya pled not guilty to her husband's murder, insisting that Donyea must have tried to incinerate her as she dozed after drinking heavily. Perhaps, she said, he'd spilled gasoline on himself accidentally and then, stopping to enjoy a cigarette before carrying out his murderous deed, set himself ablaze.

Physical evidence implicating Tonya was scarce. But the prosecution had something even more powerful at its disposal: Donyea's deathbed statement that his wife had done him in. Technically hearsay, since Donyea couldn't take the witness stand, the accusation was admissible as the "dying declaration" of a murder victimunder an exception to the rule that keeps most hearsay testimony out of court. A police officer who had interviewed Donyea at the hospital testified about what he had said, sealing Tonya's conviction for second-degree murder in November 2000.

Lorraine Roberts, Tonya's attorney, was distressed that the jury would take Donyea, through the police officer, at his word. The dead man had a history of beating his wife and of attempting suicide, and he had allegedly changed key details of his story several times in the hours before his deathsometimes Tonya tossed the gasoline as he was walking away from her, other times he was sitting on a bed. "But it was extremely difficult for these jurors to get past, 'Why would anybody say something like that if it weren't true?'" Roberts said. "We had no one to cross-examine.... There was absolutely no way to fight this. It's probably one of the worst things that can happen to a defendant."

Countless detective novels and Matlock reruns hinge on the accusatory words of a murder victim, choked out as life ebbs away. Staring eternity in the face, could someone like Donyea Jones be vindictive enough to leave a legacy of vengeance by accusing an innocent person of murder? Most people seem to believe the answer is no. After all, Christianity teaches that St. Peter shoos away liars from the gates of heaven, perhaps strengthening our conviction that a dying person just wouldn't fib.

That thinking is as archaic as the medieval English courts where the principle of Nemo moriturus praesumitur mentiria dying person is not presumed to lieoriginated. During the 12th-century reign of Richard the Lionhearted, when Christianity infused daily life, courts may have been justified in assuming that murder victims would be afraid to risk God's wrath by uttering false last words. In a secularized modern America, however, as Charles W. Quick noted in a classic article on dying declarations, "Anger, wish for revenge, and plain 'cussedness' persists in many individuals until their last breath.... The desire to justify one's own actions, to have the approbation of one's friends, moreover, may lead to conscious or unconscious falsification even in extremis."

Yet present-day courts cling to this vestige of medievalism. In recent years, many judges have used their discretionary powers to admit dying declarations that probably shouldn't have been aired in court. And too often, appeals courts dismiss these missteps as "harmless errors" that don't merit new trials for convicted defendants.

After eight centuries as a cornerstone of common law, the dying declaration exception seldom causes a stir among reformers, despite the ongoing judicial abuses. No legal organization is currently pushing for new evidentiary rules that would diminish the exception's use. Nor have legal scholars exhibited much interest in debating the issue; Quick's 1960 Howard Law Review article remains the definitive work. But that doesn't mean defense attorneys and reformers should resign themselves to a conviction every time a client is fingered by a victim's last words. Over the past decade, scientists have chipped away at such long-accepted lynchpins of criminal law as fingerprints and handwriting analysis, exposing these brands of evidence as rooted in unreliable folklore. Now they're beginning to cast an equally skeptical eye on dying declarations.

It would be too cynical to dismiss entirely the usefulness of dying declarations, which have helped to ensnare many murderers who might otherwise have escaped justice. In April 1996, a 14-year-old Florida girl named Brandy Hunt disappeared from a late-night party. The next day, two surveyors found her near a Palm Beach County swamp; she'd been wandering for 12 hours, drenched in blood from a gaping stab wound to the chest. "His name was Keith. He lives in Westgate," she told a sheriff's investigator at the hospital, before dying a week later. That sliver of information led to the arrest of 21-year-old Keith Elkins, who pled guilty to first-degree murder.

Still, there was controversy in the Hunt case. The Federal Rules of Evidence have strict guidelines about the admissibility of dying declarations, guidelines that virtually every state has adopted (with minor variations). One of the most peculiar requirements is that victims must be aware of their impending demiseas if only the certainty of meeting with one's Maker could guarantee truth. In the Hunt case, as the attorney for Elkins pointed out, a paramedic admitted that when he arrived on the scene, "all [Hunt's] injuries appeared to be not too critical," and he "told her that she was going to be okay." Hunt's statement was judged admissible only after prosecutors proved that she was well aware of the life-threatening nature of her injuries. To avoid such controversies, however, police and paramedics are often trained to level with the obviously doomed, lest their false reassurances come back to taint the victims' statements. Such honesty might not be recommended in many medical schools, since it's more likely to hurt than to help the patient, but it can be vital to a prosecution.

Another peculiarity of the dying declaration exception is that deathbed admissions from a third party cannot be used against a defendant. When Clifton Chambers died in 1988, his last words were a confession that he'd helped his son, Robert, a police chief in Marlow, N.H., bury a man named Russell Bean, whom Robert had killed by accident in a scuffle. The statement was relayed through Clifton's daughter and was enough to justify a warrant for a search on Robert's property, where Bean's body was found. But it had been in the ground for ten years and there was no physical evidence of a crime. Since Clifton wasn't the victim, his words weren't admissible, and his son was never brought to trial.

The considerable leeway that trial courts have in applying the guidelines for dying declarations, however, allows them to play fast and loose with the exception. The rules of evidence forbid testimony that includes a victim's hypothesis about the crimeanything along the lines of "I think so-and-so arranged this." But it's not uncommon for judges simply to ignore that limitation. In the 2001 trial of football star Rae Carruth, a Carolina Panthers wide receiver accused of arranging the murder of a girlfriend, jurors heard a tape of the post-shooting 911 call made by the victim, Cherica Adams, as she lay dying in her car. "I think he did this; I don't know what to think," she told the operator. The confessed triggerman was not Carruth, but Adams's dying statement helped convict her boyfriend of conspiracy to commit murder and two other charges. Carruth is now appealing his convictions, claiming that the 911 tape was prejudicial to his defense because dying declarations are supposed to be confined to victims' direct knowledge of who or what they saw.

Dying declarations aren't always declarations at all, at least in the traditional sense of verbal statements. Traumatized victims, often robbed of the ability to speak, are sometimes asked to make "declarations" through a series of nods, winks, or hand signalsphysical gestures that require a lot of interpretation from intermediaries, who typically have known the victim for no more than a few minutes. One reason that hearsay is generally inadmissible in the first place is that so much gets skewed or lost in translation. When words are taken out of the equation, the risk of mistakes increases.

Many murderers convicted on the basis of dying nods and winks have appealed, but none successfully. In one South Carolina case, the victim was able by nodding her head to identify "S" and "P" as the first two letters of her attacker's name, even though her throat was slashed so badly that her head "fell back like a PEZ toy" (in the words of a nurse who treated her). A Charleston man named Spencer McHoney was charged with her murder. Even though there was no physical evidence and McHoney passed a polygraph, he was faced with a hopeless case when the court admitted the victim's dying "statement." The "SP" declaration, relayed through the nurse, was also too stunning for the Supreme Court of South Carolina to overlook. McHoney is serving a life sentence.

If defense lawyers fail to keep a dying declaration from the jury, they have few options during cross-examination of the hearsay witness. The most popular tactic is to impeach the credibility of the victim. In the Tonya Michelle Jones case, Lorraine Roberts was able to tell the jury that Donyea had been up all night smoking marijuana. But she wasn't permitted to introduce a complete history of Donyea's suicide attempts, evidence that might have cast doubt on his mental stability and on the veracity of his final accusation.

At the same time, speaking ill of the dead seldom gets defense lawyers far. A 1996 Idaho case involved a dying declaration made by a victim whose autopsy revealed the presence of both cocaine and methamphetamine. When a police officer arrived at the roadside scene to find José Hernandez shot in the stomach, he immediately asked the victim to state his own name. "Santana," Hernandez answered. The officer then asked him to name his attacker. "Santana," Hernandez said again.

The damning autopsy report was ruled inadmissible, and a man named José Santana was convicted of Hernandez's murder. On appeal, a higher court agreed that the trial judge had blundered in preventing the jury from hearing about Hernandez's narcotics use, which might have explained why he misstated his own name to police. Unfortunately for Santana, the court of appeals' decision also included every appellant's two least favorite words"harmless error." His conviction and his 25-years-to-life sentence stand.

Rather than attacking a dead person's moral fiber, defense lawyers would be better off calling into question the reliability of a traumatized brain. In an era of DNA analysis, courts are keener than ever to hear scientific evidence based on laboratory studies. And medical research is fairly unanimous in asserting that murder victims often lack the physical ability to think or communicate rationally.

Bryan A. Liang, a University of Houston law professor, is the foremost advocate of this tactic. A medical doctor as well as a lawyer, Liang has spent considerable time in emergency rooms tending to trauma victims, witnessing firsthand the impaired mental functioning of the gravely injured. "When a person is opened up with a knife wound or is shot, we don't even think of taking their history, because we know we're not going to get anything out of it," he said. "When somebody is deprived of oxygen, when they're bleeding out of every orifice, [they] just simply are not going to be reliable and sharp-edged intellectually."

Conducting laboratory experiments on the neurological constancy of the dying is impossible, since their relative dementia before and after the mortal wound can't be gauged. But according to Liang, researchers have been able to mimic the effects of mild trauma on cognition by placing test subjects in barometric chambers, which simulate rapid, oxygen-depriving changes in altitude. A 1989 study in the journal Aviation, Space, and Environmental Medicine found that healthy young males who underwent such treatment suffered from severely limited functioning, particularly in "intelligence, reasoning, and short-term memory." It can sensibly be assumed that the effects would be even more extreme for a person whose hypoxia was due to a shotgun blast or extensive third-degree burns.

Liang is the only scholar in the past 40 years to have written extensively on dying declarations, and he knows of no case in which medical experts were called to question a dying declarant's cognitive functioning. Defense attorneys prefer to stick with their age-oldif largely hopelessstrategy of character assassination. "If they just brought up academic experts, they could tell you how long it takes for a lack of oxygen to change brain functioning...and how the experiments in the barometric chambers found reduced cognitive function as defined by brain activity," Liang said. Or a showman lawyer could ask jurors to try hyperventilating to the point of passing out and then saying the alphabet backwards. Try itit's not easy, but it's surely a great deal easier than recounting the facts of one's own murder while suffering from a gaping chest wound.

Lorraine Roberts, however, seems sure that no jury could be convinced to distrust dying declarations, which have had centuries to soak into the collective imagination. "It puts the defense lawyer in an unbearable position," she said. In the Jones case, not a single prospective juror interviewed to sit on the case expressed any skepticism about the veracity of a murder victim's last words.

Brendan I. Koerner, a fellow at the New America Foundation, last wrote for Legal Affairs about forensic science.